Ongoing research by Dr. Mark Mazzola, plant pathologist at the U.S. Department of Agriculture, suggests incorporating oil-seed meals into the soil before replanting an orchard might help combat replant disease.      Mazzola, based in Wenatchee, Washington, has been exploring biological alternatives to the standard treatment of fumigation with Vapam (metam sodium) or Telone C-17 (dichloropropene and chloropicrin). Methyl bromide is rarely used to fumigate Northwest orchard soils because it is being phased out of use and is comparatively expensive. Replant disease in Washington appears to be caused by a complex of organisms in the soil, including the fungi Cylindrocarpon, Phytophthora, […]